Synthesis of Hydroxyapatite Nanorods by Hydrothermal Recrystallization Method

Hydroxyapatite nanorods were prepared by hydrothermal recrystallization method using Ca(NO3)2 and (NH4)2HPO4 as raw materials. XRD, TEM, HRTEM and FTIR were used to characterize the hydroxyapatite nanorods. The effect of pH value, crystallization time were studied on the compositions and structures of hydroxyapatite nanorods. The best aspect ratio of ca. 28 could be obtained for the hydroxyapatite nanorods prepared by hydrothermal heat-treatment at 180 ℃ and recrystallization of the room temperature mixture of the suspension at pH value 7.5 and the clear solution of pH value of 10.5. With different pH values of clear solution, as monomer concentration (chemical potential) changed, the aspect ratio of hydroxyapatite nanorods were different; when crystallization time elongated, the aspect ratio of hydroxyapatite nanorods was increased first, then decreased.